Drill bit



July 18, 1939. G. A. MEAD I DRILL BIT Filed May 27, 1938 In venlor Patented M 18, 1939 UNITED STATES PATENT OFFICE Application May 2'1, 1938, semis. 210.351

SClaims.

10 extending from the bit to the surface of the earth where it is driven by meansof table In my invention the rotary cutters are supported in part byremovable arms which may be a I rotatin readily detached from the bit for the purpose of renewing such arms as may be worh and also suchcutters as-need replacing.

One object of my invention is to provide means for holding the arms in assembled relation and which means will tend to more firmly secure the arms in position as the drill bit rotates as later herein explained. Y

Other objects will be the disclosure which follows.

25 In the drawing:-

Fig. 1 is a side vertical view of my invention in partial secti'on aiid shown attached to a drill pipe. I

Fi 2 is a vertical side view in section of my all invention shown in Fig. 1 taken on the vertical.

plane .at right angles to the vertical 'planeof- I Fig. 1, but Withdllt the drive mechanism shown in Fi 1.

, Fig. 3.15 a horizontal section taken on the'line 35 3-4 of Fig. 1.

Referring to Figs. -1 and 2, Ishow'a hollow drill pipe [externally threaded on a taper and attached to a coupling 3 by like threads. The

- coupling is threaded internally 'at one end on a 40 taper to receive the threaded tapered portion or stem 3 which forms an integral projecting part of thebodyt- The .body is "provided with tour vertical and angularly disposed slotsland 3 to. receive the 45 detachable arms] and 3 respectively and "the body is provided with a grooved shoulder 3 projecting into each slot and having an inwardly and downwardly sloping side surface l3. Thebody is also provided with a central axial 60 passage Ii having a circumferential shelf l3 with an opening l3 therethrough. I I

The arms are each provided with an inwardly extending grooved shoulder ll having an inwardly and upwardly sloping side surface to correspond as with the surface II on the body shoulder, the

is preferably provided with romade"evid'ent through (class-m shoulder ll being-arranged to interlock with .the shoulder 3.

The upper end of each arm is provided with a flange i5 forming a depressed shoulder l6.

L The body is further provided with a threaded 5 cylindrical portion II as distinctfromthethreaded tapered portion 3 and I preferto thread the portion H with a left-hand thread while the por-' tion 3 is threaded right-hand. Theportion I! may, of course, be threaded right-hand if desired.

In the past it has been the practice to place the collar]. upon the tapered drive thread but I prefer to use a separate and cylindrical portion I I for the collar as less close machining is necessary'. V

Mounted onthe threaded portion I1 is a collar l3 threaded according to the portion i'l and provided with a flange Hi to interlock with the flange l5 on the end of the arm and to engage the shoulder l6 thereon. 0

When the arms are placed in position, with the shoulder 3 and I I interlocked and the collar I. in place and interlocked with the flange IS,

the arms will be securely held against removal ofthe slotsiand 6.

' The directionof rotationof thedrill bit is usually clockwise looking down upon the bit when in its normal operating position and this tends.

the bit while drilling as the threads are right-- handed. w

If the collar J3 and body l be threaded righthand the friction between the collar and the side wall of the hole during drilling or between left-hand, 3 previously pointed out, the mam 4o will tend to rotate the collar relative to the hi t to further tighten the collar upon the arms during rotation of the bit ina clockwise direction. In some designs of my invention the diameter of the collar I. may more nearly approach the diameter across thev arms at the lower end of the bit than is shown in Fig. 1, therefore, the tendency for the collarto rotate relative to the bit in such a design would be greater as the fric-, tion upon the collar l3 and hence the force tendto ing-to rotate the collar wouldbe more positive in action since the diameter of 'the collar is greater.

The end of the coupling 2will tend to constantly move towards and into engagement with the collar 13 during drilling if theparts have/ and they willbe braced sideways by the side walls 25 tofurther secure or tighten the coupling 2 upon a.)

been accurately machined and will act as a lock for the collar, but this is not necessary when the collar is threaded left-hand as I propose.

If the portion I! were threaded right-hand then any rotation of the coupling 2 in a clockwise direction (as previously described) relative' It will be evidentthat with my invention the arms will be held securely in place during drilling with a tendency toward the automatic tightening of the collar upon the arms and of the coupling 2 upon th collar It or upon. the stem; in any event the collar tends to tighten upon the arms as the bit rotates in a clockwise direction should slack occur between such parts.

The arms 1 are each provided with a cutter l9 mounted on a stud 20 shown as an integral part of the arm. a

Mounted on and secured to the bit is a support 2| having a stem portion 22 extending into the passage H and having its upper end threaded-to receive the nut 23 to hold the support in place with the shoulder 24 in engagement with the shoulder 25'. 'lhe support has a downwardly projecting arm which has a through opening 21 to receive the shaft 28. The vertical central axis of the arm) is positioned to one side of the vertical axis 1-3: of the bit as shown in Fig. 2, thus permitting the use of a long and short. cutter II and 3| respectively mounted on the'shatt 28.

The shaft 28 has its ends mounted in openings in the arms 8 and held in placeby pins 3! and the studs 2|! have their ends supported inrecesses in the arm It.

The openings 32 permit the use of a spanner wrench-in tightening the collar ll against the arms.-

The support 25 has a passage 33 with side openings ll through which water may be forced fromabove onto the cutters to clear them of debris and force the same to the surface of the ground through the space between the drive pipe and the side wall of the hole being'drilled.

While the general practice is to thread the body of the bit tapered to take the drill pipe, the body may be threaded straight.

If desired, the drive pipe end may be internally threaded on a taper and be directly attached to the body, thus-omitting the coupling 2.

As my invention, I claim:

1. A drill bit comprising a body navmga plurality of downwardly projecting arms, each arm being detachably secured to the bodyand cartying cutters at the lower ends thereof, interlocking shoulders on the arms and body and a collar mounted on the body to engage and interlock with the ends of the arms to prevent disengagement of the arms relative to the body, the

" body and the collar. provided with cooperating left-hand threaded cylindrical portions whereby the collar may be moved into engagement with the arms by rotation of the collar 'in an anticlockwise direction relative to' the body arm a threaded projectingtapered stem on the body to receive a drive pipe whereby the bit is-rotated.

2. Ajdrill bit comprising a body,'a plurality of detachable cutter carrying arms associated with the body, threaded tapered means on thebody for attachment to a drive mechanism torotate the bit 'in a clockwise direction, a lefthand threaded cylindrical portion on the body, threaded clamping means mounted on the threaded cylindrical portion to engage and hold the arms in position on the body, the said clamping means being so arranged as to be engaged by the end or the drive mechanism to lock the clamping means in place when the bit is operated.

3. A drill bit comprising a body having a righthand thread at one end to attach it to a driving mechanism, a plurality of arms detachably connected with the body and each adapted to support a cutter, the body having a left-hand thread adjacent one end of each arm, a clamping 'member mounted on the body and interlocked. with .the left-hand thread to engage and hold the arms in position, the attachment of the bit to. the

driving mechanism and the pressure of the clamping member upon the arms tending to increase independently of each other as the bit rotates in a clockwise direction.

4. A drill bit for sinking a hole in the earth and adapted for rotation in a predetermined direction by a driving mechanism comprising a body having a plurality of detachable cutter carrying arms, clamping means mounted on the body and engaging the arms to hold them in position and to take .up any slack between the arms and body which may develop during drilling,

independent of the driving mechanism providing the clamping means is rotated inthe'opposite from the aforesaid direction relative to the body through engagement of the clamping means'with the surrounding earth, and cooperating means associatediwith the body and clamping means to effect the aforesaid functions.

5. A drill for sinking a hole in the earth comprising a bodyfa plurality of detachable cutter carrying arms associated with the body, a threaded portion on the body for attachment to I a driving mechanism to rotate the bit, a cylindrical portion on the body adjacent the said threaded portion, a clamping ring mounted on the cylindrical portion to engage and hold the arms in position on the body, 'means upon'the surface of the cylindrical portion interlocked with means upon the clamping-ring, the interlocking means between the clamping'ring and the body;

being such that a tangential force applied to the periphery of the clamping ring. through friction of the clamping ring with the earth as the bit rotates in a clock-wise direction will tend to rotate the clamping ring and move it longitudinally toward the arms,, I v

6. In a drill bit for sinking a hole in the earth comprising a body, a plurality oi demountable cutter carrying arms associated with the body, means on the body to receive a driving mechanism to rotate the bit in a clock-wise direction, a clamping ring mounted on the body in interlocking relation, thereto to engage and hold the arms against becoming loose, the'combination with the clamping ring and the. body of means to interlock these parts together whereby the clamping ring will tend to move longitudinally oi and toward the arms thrdugh tortional force applied to the clamping ring external of the bit 'and driving mechanism while the bit rotates in a -'clock-wise direction to take up slack or wear between the arms and clamping means which may develop while the bit is drilling,

-7.Adrllihoadcomprisingabody.a plurality of demountable cutter carrying arms, threaded means on the body for attachment to a rotatable driving member to rotate the head in one direction, means to clamp the cutter carrying arms in position on the head, the said means including. a clamping ring mounted on the body and provided with threads opposite in effect to the aforesaid threads whereby the resistance to rotation of the drill head during drilling will tend to effect a tightening of the drilling member upon the body and the engagement of the clamping ring with the surrounding earth during drilling will tend to tighten the clamping ring upon the arms and automatically eliminate any looseness between the arms and body and the clamping ring which may develop during drilling.

8. A central member for a drill bit adapted to support a plurality of cutter carrying arms comprising a body having a plurality of means spaced around its outer surface adapted to interlock with means on cutter carrying arms to assist in holding. the arms in position on the member, a projecting tapered portion having its surface provided with a thread to receive threaded driving means whereby the driving means will tend to. tighten upon the tapered portion when the member is rotated, a cylindrical portion bebetween the arms and central member during the drilling operation. 9. Adrill bit comprising a body, a plurality of demountable arms carrying cutters at the ends thereof, means on the body to attach it to a driving mechanism whereby the bit may be rotated in a predetermined direction, a clamping lring mounted on the body. and movable longitudinally toward the arms when the clamping ring is rotated in the opposite direction to the said predetermined direction relative to the body to engage the arms and hold-them securely in position on the body and means on the body interlocking with means'on the clamping ring to aflect the said longitudinal movement of the ring.

GEORGE A. MEAD. 

